Use plugin_path to improve path logic...

Added in Galaxy commit https://bitbucket.org/galaxy/galaxy-central/commits/ddc9a669d53aa259d38efc882c890503444daaf5. Added it to Galaxy cleanup the code and this is the result - oh well :) - it is at least more techically correct.
Use get_api_key() to fetch Galaxy API key...

This is a more appropriate abstraction layer to work at and provides the added benefit of auto-generating the key if it doesn't exist.
Merge pull request #14 from jmchilton/gxpr450

Update plugin for Galaxy Pull Request #450